Detecting changes in HTML page sources - dgtlmoon/changedetection.io GitHub Wiki

For some webpages, relevant information is best accessed by checking the HTML page source.

Use Case

For example, the HTML response of web shops like https://www.campuspoint.de contains the product listings in JSON format which is then processed client-side with JS to produce the final markup. One could use the JS-enabled Playwright-content-fetcher for such a webpage, but checking against the page source is more efficient.

Approach

• In the General tab, prepend the target URL with source: (example: source:https://www.campuspoint.de/mobile/notebooks/lenovo/thinkpad-t-serie/thinkpad-t14s.html)
• In the Request tab, choose the "Basic fast Plaintext/HTTP Client" fetch method
• Choose a suitable trigger in the Filters & Triggers tab, for example the regex-based "Extract text" one.
  • Example: use /"product_count":(\d+)/i to check when campuspoint.de adds new models of a certain laptop series to their inventory.

more at https://changedetection.io/tutorial/source-code-monitor-how-get-alerts-changes-html-source-code